One issue with cloned plants is that they are all the same. Yes, they may all yield the same delicious corn- but if one thing goes wrong, that would be detrimental.
What if that one clone population of corn was weak against one type of mold, for example? If that mold was able to infect just one- it'll eventually spread like wildfire to all the other clone plants & wipe out an entire crop.
That would be a huge waste of money, time, resources &, most saddening of all: no corn...
So, the answer choice should be C.
Hope that helps!